Grinding, lapping, or polishing machine for diamonds or other crystals and the like



May 1, 1945. F. c. JEARUM LAPPING, OR POLISHING MACHINE FOR GRINDING,

DIAMONDS OR OTHER CRYSTALS AND THE LIKE Filed April 6, 1945 Patented May 1, 1945 I 7 2,374,751 I v GRINDING, LAPPING, on POLISHING MA- CHINE FOR DIAMONDS .TALS AND THE LIKE Frederick Charles J e'arunnSutton, England Application April 6, 1943, Serial N 0. 482,008-

In Great Britain May 16, 1942 a 9 Claims. (c1. 51-429 This invention relates to machines for grinding or lapping or polishing (hereinafter referred to as lapping) diamonds or other crystals or minerals .(hereinafter referred to as stones) for industrial purposes or for the jewellery trade, upon a lap or revolving cutting disc or scaife (hereinafter called a scaife) and the invention has for its object the lapping of stones to provide perfectly fiat faces or tables thereon andto provide exactly parallel and flat faces on the opposite sides of the stones (such as for examplefor producing parallel facets on opposite sides of a stone for making a diamond.

or like die), and includes the provision of means to facilitate ready inspection from time to time of the lapping operation and convenient inter-v change of dops.

A further aim of the invention is toprovide means adapted automatically to find the cutting grain of a diamond or other stone having a particular cutting grain without the skilled inspection and setting of the stone usually required for the purpose of finding the grinding position.

The invention consists in a machine of the type indicated having a tang, the axis of which is fixed in a horizontal plane, and a head on the end of the tang adjacent the scaife comprising: a vertical slideway, a slider freely displaceable vertically on said slideway underor against gravity action, a dop or stone mount having a barrel or body provided with a coaxial rotatable member carryin stone holding means, a vertical bed on said slider open to receive said barrel and shaped to locate said .barrel laterally with the axis of the rotatable member vertical, complementary interengaging means on the barrel and bed'for locating the barrel longitudinally of the bed and releasable clamping means for securing said interengaging means, the arrangement bein such that when seated on the bed the barrel and rotatable member are confined to the vertical displacements of the slider.

OR OTHER CRYS- tachable slideway block 2 for a tang or arbor 3.. The block on its underside has marginal bevelled flanges to fit the bevels l a of the bed and is adapted to be releasably coupled to the bed bymeans of a T-headed member 2a (fitting in the longitudinal groove of the bed) carried by a sheave engaged with an eccentric 2b mounted'on a horizontally rotatable pin having an operating handl 2d at the side of the block. Thejblock is provided with a slideway 2e of diamond-or square shape in crosssection, a diagonal of the square or diamond'being positioned in the 1 vertical plane. Theslideway may-be horizontally divided and formed in two halves connected together bybolts or set screws and a set screw *2) is provided inthe upper half of the slideway for locking the tang infany'adjusted position.

Thetang 3 comprises a horizontalybar of cor- I responding cross-section to the slidewa'y into which it fits and has at its forward and rear ends on its underside anchorages 3a, 3b (the anchorage 3b of which may be adjustable for tension by manipulation of the nut for a wire orribbon 3d which is lapped around adrum on 'a, trans- Further features of the invention will be hereinafter described and defined in the claims;

In the accompanying drawing-- Fig. I is a side elevation partly in section of a machine constructed according to one form of the invention;

Fig. 2 is a plan view to Fig. 1; while Fig. 3 is a rear end elevation of the machine.

In carrying the invention into effect according to one convenient mode as described by way of example, a horizontal bed I having bevelled edges la anda longitudinal slot lb of :inverted T shape in cross-section is provided as a-lmountfor adeof the machine according verse spindle 3e mounted'in horizontal bearings in the slideway block. The spindle has a milled head 3] or other manipulating held for rotating the drum,'for winding the tang and fro longitudinally in the slideway. At the forward extremity of the tang ahead 4 is provided in which is formed a vertical geometric 'slideway 4a having vertical sets of ball bearings 4b adapted to receive a tool bed slide member 5.

The bed of the member 5 is in plan of V shape or has a double bevelled channel (as seen at 5a, Fig. 2) for receiving and seating the cylindrical barrel 6 of a mechanical dop or like tool mount for the stones to be treated. The mechanical dops for use in the apparatus may be interchangeable and each have a'horizontal his: to fixed tothebarrel and adapted to extend into a cavity at the base of the bevelled or 'V-shaped bed. The lug has a verticalbore into which is fitted the eccentric portion 1 of a vertically rotatable pin la insertable in a bore in the bed 5,. the arrangement being such that when the pin is inserted and rotated in the lug bore the eccentric clamps the barrel of the dop upon the bed.

The barrel is formed to serve as a mount for a vertical sleeve 8. The sleeve is carried in double bevelled bearings and has upper and lower coni cal shoulder membersv 3a for engaging the bevels.

The lower shoulder is in one,,with or fixed on the sleeve while the upper shoulder is slidable weights l2f forv loading: the-stone.

' upon wheel 9 is keyed upon the thread 812' between the nut 8d and the upper conical member 8a. Brackets I support a worm lfla with which a flexibledrive shaft lllb is coupled.

.This revolution of the stone constantly turns the cutting grain of the stone about. thevertical been determined the tang islocked by the set screw.

Assuming that the stone has been set upin the gripping fingers I laupon the spindle support 12 in the mechanical dop and the latter placed in position with its lug 6a locked by the eccentric spindle la, the raising and lowering lever l3 is manipulated to; lower the stone intofcorrtact with the scaife when'the lapping operation proceeds, the weight l2d andthe counterweight I4 having -"been adjusted to afford the desired degree of lapping; pressure.

axis so that the grain is automatically exposed atleast twice in each revolution. to the fiow 'of the abrasive grains carried by the scaife; 1

At the lower end the sleeve carries ahead II.

in which is mounted a pair of pivoted stone grip ping. levers or fingers. I I a operatedtby slide: blocks in; engagement. with rightand left-handtscrew threads (not shown). of anactuating; member having a milled: manipulating head" Mb.- The grippingv fingers are adapted to; engage. a: stone upon either side,-the stone being. rmsitioned; vertically upon a flatbasa supportvin tha form ofi a short spindle l2a. mounted in the bore ofthe sleeve and adapted to be adjustedlongitudinally withrespecttothe gripping members byan abrutting; spindle [2b oi a micrometerscrew' device-1.2a whichmay be calibrated The longitudinal.posi v tion of thesupportspindle lZwfor. the stone may be lockedby aset screw l-2d ente i -horizontally in the gripper head. The. rotational adjustment of the. head may be determined :orobservedby aid of a scale or index. p 1 I j The vertically sliding bed 5;; 5a,- is engaged by, or has a depending post 5b: enga ed by means adapted to bring vertical pressure toibear thereon for the purpose. of; lifting; -the stone ofi -tthe scaife and lowering,- it into, position: again as required. These means may. comprise ai leveri t3 pivotedat theiorward. endlof: the tang amt hazv ing' one arm extending below. the postabove: referred to, so that thelatter; rests thereon while the other extends. rearwardlyas a manipulating handle which, when depressed, immediately raises the stonesoff the .scaife. 'Ilhehandle: may-0on veniently' be in the form of a. slotted- -counter-e weight M longitudinally adiustable -on the-lever and secured by-a screw- I40... g

The vertical slideway of the tang heagli is prac tically frictionless so that the stone rests and is automatically fed downwardlyfl'upQ rthe-scaife 15 by. gravity as the lapping operation. proceeds; The, slideway Or the. mechanical, dop may; have a, vertical. rod or other means. for. attaching-La weighting .disc or discsin order. to vary the-.pressure with which. the, diamond engages-the scaife, for example the micrometer spindle may have an extension; rod- 12a. for receiving awseriesr of The horizontal bed- I. uponywhi hrthe-slideway block 2 is mounted may bepositioned; radially of the scaife. or'at a tangentthereto, (in-parallel to a radius of; ora tangenttouthe scaife, andpthe horizontal position of. the dopmayberoughly eifected by locating the slideway block upon the bed and locking'it by the T, head locking device.

The radialposition of the path of' the: stone the scaife may be adjusted: to a nicety by the operation of the milled headed'spindle 3e carrying the drum driving the tang winding tape. When thechosen radial position of the stone has The progress; of lapping can be readily observed from time to time. by depressing the lever 13 to raise the stone off the scaife and the dop can be immediately released by a turn" and withdrawal of. the eccentric: spindle 1a. When the stone has beenzcbserved the mechanical dop is returned to itsposition on the vertical bed and relocked in position by reinserting and turning the spin- 61182112 in thebarrel lug; oi the: dop.

It: willl be. a preciated ,that=the.-.stone.holding head may lee-adapted to: secure stones. of awariety of shapes and thatheads-maybepronzidedrwhieh particular stone may be selected" and placed. in

position.

In addition. to; employing-the invention tor-the slider,-freely displaoeable verticallyg on saidslideway under or againstgravity action stone .mount' having; barre-11., or hewith a. coaxial rotatable member: can

holding means avertioal bedronasaid; sliden; open to. receive said barrel and shaped tnllocateksaid barrel laterally with. the? axis, of rotatable member, vertical. complementary, interengaging means. cm the. barnell and bed; for locating ,the barre-l; longitudinallymof: the bed and releasable clamping means: for secuning said interenga-ging meanspther arrangement. being; such; thaowhen seated on the bed: the abarrel: and. rotatable mem her are confined: to the. ventical clis-placementa of thesli'der. v .21.

2. A machine: of the: type indicated 'havinggf a tang; the axis. of whichiis tfixedi in: a horizonta-l plane, and a: head :on the EIldPOf. the tang-radia cent the scaife comprising: afventical-slidewaw, a slider ifreely'displaceableverticallm onsaidslidw way: under. or against gravity: action ,a.;dop.; or a; barrel; on. body; provided with a coaxial rotatablei memberrcarrying; mes chanical stone holding means; having;,;g ripping fingersanut a-flatbasa support fonthe stone, a

vertical bed on said: :slide'r open-Ito receive: said barrel and shaped:towlocatersaidx barrel laterally with the' axiszofl the rotatable member vertical,

complementary 'inteinngagingzmeans: on memerel and bed for locating the barrel ilon'gitudienally ofuth bedvand. releasable-clamping: means for securing said interengaging means; tho ax ra-rzgement being such. thatrwhenz seatediohF-the bed the 'barrelzandi rotatabiei membenrare confinedto the?vertical":displaoementsiofatheslider. 3= A. machineofi theitypeaindicatedi hflflingra tang; theaxis of' whichl is lirted imtxhonizontml plane radially; of the -scaife'; I anu ai headi mane are interchangeable sotthat a head-suitabletma end of the tang adjacent the scaife comprising: a vertical slideway, a slider freely displaceable vertically on said slideway under or against gravity action, a dop or stone mount havin a barrel or body provided with a coaxially rotatable member carrying stone holding means, a vertical bed on said slider open to receive said barrel and shaped to locate said barrel laterally with the axis of the rotatable member vertical, complementary interengaging means on the barrel and bed for locating the barrel longitudinally of the bed, releasable clamping means for securing said interengaging means, and means for rotating the said coaxial member and stone automatically to find the cutting grain of the diamond.

4. A machine as claimed in claim 1 wherein the complementary interengaging means comprise a lug on the barrel adapted to enter a cavity in the bed and formed with a vertical bore, and wherein the clamping means comprise a withdrawable rotatable spindle carrying an eccentric for the, lug bore, the arrangement being such that rotation of the eccentric carrying spindle binds the barrel onto the bed.

5. A machine as claimed in claim 1 wherein the slider has a post and a manipulable lever is provided adapted to bear upon the post so that I by manipulation of the lever the dop maybe quickly raised to place the stone out of contact with the cutting disc.

6. A machine as claimed in claim 1 wherein.

the slider has a post and a manipulable lever is provided adapted to bear upon the post so that by manipulation of the lever the dop may be quickly raised to place the stone out of contact with the cutting disc andwherein the lever is provided with an adjustable weight for counterweighting the slider and dop to the desireddegree and wherein the dop is provided With means for adjustably receiving loading weights.

7. A machine as claimed in claim 1 wherein the tang is mounted in a horizontal slideway, the tang and slideway being of non-circular crosssection to prevent rotation of the tang about its horizontal axis and wherein means are provided for moving the tang axially along its 'slideway to vary the radial position of the lapping path occopied by the stone on the cutting disc.

8. A machine as claimed in claim 1 wherein mechanical drive means are provided for continually rotating the stone carried by the dop about its vertical axis.

9; A machine as claimed in claim 1 wherein between the adjacent sides of the slider and its slideway, ball races are provided to afford a substantially frictionless displacement of the slider under gravity action.

FREDERICK CHARLES J EARUM. 

